European patent application No. 85304848.6 (published Jan. 22, 1986 under publication number 0169016) describes two bovine bone-derived CIFs, designated CIF-A and CIF-B. Both have molecular weights of approximately 26,000 daltons by SDS-PAGE analysis and are dimers. They each exhibit in vitro chondrogenic activity by themselves, as measured by cartilage specific proteoglycan (PG) production in an agarose gel culture model using fetal rat mesenchymal cells. Neither, however, is chondrogenically active in vivo by itself. Amino acid sequencing of CIF-A showed that it has a partial (30 amino acids) N-terminal sequence identical to that reported for a human placenta-derived polypeptide called beta-type transforming growth factor (TGF-.beta.). The partial N-terminal sequence of CIF-B is different from that of TGF-.beta. (eleven of the first 30 amino acids at the N-terminus are different). Both CIFs exhibit activity in the TGF-.beta. assay (ability to induce anchorage-independent growth of normal rat kidney cell colonies in soft agar).
Copending U.S. patent application Ser. No. 836,672 filed Mar. 6, 1986 discloses that both CIFs possess anti-inflammatory activity and are inhibitors of mitogen-stimulated T cell proliferation and B cell activation. It also reports that CIF is localized in centers of hematopoiesis and lymphopoiesis and that CIF may, therefore, be useful for treating indications associated with malfunction or dysfunction of hematopoiesis or lymphopoiesis.
TGF-.beta. derived from bovine kidney, human placenta, and human platelets is described in International patent application No. PCT/US83/01460, published Mar. 29, 1984 under no. WO84/01106, EPA No. 84450016.5, published Dec. 19, 1984 under No. 0128849, and U.S. patent applications Ser. Nos. 500,832, 500,833, and 500,927, filed June 3, 1983. These applications present data showing that such TGF-.beta., when combined with EGF or TGF-.alpha.L, promotes cell proliferation in the above mentioned soft agar culture assay and promotes cell proliferation and protein deposition in a rat soft tissue wound healing model.
TGF-.beta. has been shown to be very similar to, if not identical to a polypeptide identified as growth inhibitor (GI) purified from BSC-1 monkey kidney cell-conditioned medium (Tucker, R. F. et al, Science (1984) 226:705). TGF-.beta. and GI have both shown the ability to inhibit growth of a variety of tumor cell lines (Assoian, R. K. et al, Cancer Cells 3/ Growth Factors and Transformation, Cold Spring Harbor Laboratory, June 1985, pages 59-64 and Moses, H. L. et al, Cancer Cells 3/ Growth Factors and Transformation, ibid, pages 65-71).
U.S. patent application Ser. No. 602,520, filed Apr. 20, 1984, describes a group of factors referred to as tumor inhibiting factors (TIFs). These factors were partially isolated from serum-free conditioned media derived from the human tumor cell line A673. The factors are reported to have molecular weights of 28,000 daltons, 10-16,000 daltons and 5-10,000 daltons, to be antagonistic to the activity of TGFs on anchorage independent growth of tumor cells in soft agar, and to inhibit in vitro proliferation of various human and animal tumors.
The present invention is based on the findings that CIF-A and CIF-B possess oncostatic activity.